“Costal cartilages firmly ossified. Posterior ribs losing their capitular articulation, and only uniting with the transverse processes of the vertebræ by the tubercle. Anterior (2-6) cervical, in most, ankylosed together. Pterygoid bones short, thin, involuted to form, with a process of the palatine bone, the outer wall of the postpalatine air-sinus. Numerous teeth in both jaws (_Monodon_ excepted), sometimes deciduous. Symphysis of mandible short or moderate, never exceeding one-third the length of the ramus. Bones of the skull not raised into a distinct crest behind the anterior nares. Orbit of moderate size. Lachrymal bones not distinct from the jugal. Pectoral limbs varying much in form and size. Dorsal fin usually present.”—_Flower._ Tribe I. _STENONINA._ Stenonina, _Gray_, _Synops. Whales & Dolph._ p. 5. Head beaked, teeth conical. Beak of the skull elongate, slender, compressed. Nasal triangle short. Symphysis of the lower jaw elongate. 1. STENO. Steno, _Gray_, _Cat. Seals & Whales_, pp. 230, 232, 393, 394; _Synops. Whales & Dolph._ p. 5. Beak of the skull compressed, higher than broad. Symphysis of the lower jaw long. Marine and fluviatile. “Pectoral fin moderately long, triangular, obtusely pointed at the end. First digit short, without any bony phalange; the second with six, the third five, the fourth two, and the fifth one phalange. The carpal bones all separated by broad cartilages. Scapula oblique, truncated at the posterior angle. Acromion broad, and coracoid rather small.”—_Flower._ a. _Skull large, solid; the beak compressed, high._ * _Teeth large, conical, about two in an inch of the length of the margin of the jaw._ 1. Steno frontatus. B.M. Steno frontatus, _Gray_, _l. c._ p. 233. n. 3; _Synops. Whales & Dolph._ p. 5, t. 21. f. 7, 8. Beak of the skull short; the front part thick, high, and blunt. Teeth 24·24, large, two in an inch. Inhab. Indian Ocean. 2. Steno compressus. B.M. Steno compressus, _Gray_, _l. c._ p. 233. n. 4; _Synops. Whales & Dolph._ p. 5, t. 27. Beak of the skull elongate, compressed, attenuated in front. Teeth 26·26, large, two in an inch (Zool. E. & T. t. 27). Inhab. South Sea. _Steno rostratus_ appears to belong to this section. ** _Teeth three in an inch._ 3. Steno chinensis. Delphinus chinensis, _Osbeck’s China_; _Gray_, _Cat. S. & W._ p. 266. Delphinus sinenis, _Desmarest_, _Mam._ p. 514; _Flower_, _Trans. Zool. Soc._ vol. vii. p. 151, t. 17, 18 (skeleton). Vertebræ 51:—C. 7. D. 12. L. 10. C. 22. Inhab. China, Canton (_Osbeck_), Formosa (_Swinhoe_). b. _Skull small, rather spongy. Teeth small, slender, attenuated, about four or five in an inch of the length of the margin of the jaw._ * _Beak of the skull elongate, compressed, much attenuated and acute in front. Teeth four in an inch._